Hydroconversion catalyst

ABSTRACT

A method for making a hydrotreating catalyst wherein the catalyst is prepared by mixing a peptized hydrated supporting oxide with a hydrated Group IVB metal oxide gel promoter. The Group VIII metals are mixed in with the Group IVB metal oxide gel promoter. A solution containing a soluble Group VIB metal and a basic compound is added. The catalyst is used for hydrodenitrogenation and Ramsbottom Carbon Residue reduction of a hydrocarbon feedstock.

This application is a divisional of application Ser. No. 07/543,257,filed Jun. 25, 1990, now U.S. Pat. No. 5,089,462.

BACKGROUND OF THE INVENTION

This invention relates to hydrotreating of hydrocarbon feedstocks andmore particularly to catalytic treatment of hydrocarbon feedstocks toeffect removal of nitrogen and sulfur, and to reduce Ramsbottom CarbonResidue (RCR). This invention is especially directed toward thepreparation of a catalytic composition having excellent hydrotreatingactivity for the removal of nitrogen and reduction of Ramsbottom CarbonResidue in heavy hydrocarbon stocks. Examples of such heavy stocks aretotal crude oil, crude residue, atmospheric and vacuum gas oils, cycleoils and lube oils.

Crude petroleum oil, and heavy hydrocarbon fractions and/or distillatesderived from crudes, contain components such as nitrogen, sulfur andmetals. These impurities may exist in heteratomic compounds and areoften present in relatively large quantities. Such impurities may poisonor modify catalysts used in the upgrading of petroleum fractions inreforming or cracking steps. Nitrogen and sulfur are also objectionablebecause combustion of hydrocarbon fuels containing these impuritiesreleases nitrogen and sulfur oxides. Such byproduct gases are noxious,corrosive and present a serious problem in the field of air pollution.

The removal and/or conversion of these impurities is effectively carriedout by catalytic hydrotreating, where a feedstock containing sulfur andnitrogen is contacted with a supported catalyst in the presence ofhydrogen. Hydrotreating conditions may include a wide range oftemperatures, pressures and space velocities as determined by the designof commercial refineries.

Supported catalysts can be generally characterized as comprisingmetallic components, supported on a refractory inorganic oxide carrierof synthetic or natural origin and having a medium to high surface area(typically greater than 50 m² /g) and a well-developed pore structure.Metallic components having hydrotreating activity may include the metalsof Groups VIB and VIII of the Periodic Table. The "Periodic Table" asherein referred to appears in the 62nd Edition of the Handbook ofChemistry and Physics, CRC Press Inc., Boca Raton, Fla. (1981).

Group IVB metal components (for example, titanium) can be incorporatedinto the catalyst as a promoter to increase the activity of thecatalyst. Phosphorous components are commonly incorporated into thecatalyst to improve its activity by increasing its acidity; however, theprior art (U.S. Pat. No. 3,840,473) has taught that when the presence ofphosphorous is greater than about 0.5% by weight in atitanium-containing catalyst, phosphorous is detrimental to the activityof the catalyst.

Numerous disclosures have been made directed to methods for preparingsupported catalyst for hydrotreating. Catalytic metals may be applied toa formed or unformed carrier by several methods known in the art whichinclude co-precipitation of the support with active metals and promoter(also known as the cogel method), mixing the active metals and promoterinto a peptized substrate, and by various impregnation procedures onpreformed substrates.

U.S. Pat. No. 3,401,125 discloses co-precipitation of the support withactive metals including Group IVB to give an active hydrodenitrogenationcatalyst. This method requires washing steps which are expensive, andmetals, particularly the molybdenum, may be partially washed off thecatalyst.

U.S. Pat. No. 3,897,365 discloses a process for preparing ahydrotreating catalyst comprising mixing molybdenum with an inorganicoxide gel consisting of at least 50 weight percent alumina, up to 50weight percent silica, and up to a total 10 weight percent titania. Themolybdenum oxide is from 5 to 15 weight percent. The catalyst is furtherimpregnated with phosphorous, nickel and molybdenum.

The process for preparing a hydrotreating catalyst described in U.S.Pat. No. 3,897,365 differs from the method of our invention in that ourinvention involves mixing the Group VIII and Group VIB metals ratherthan impregnating these metals into the organic support.

U.S. Pat. No. 4,196,101 discloses a process for preparing ahydrodesulfurization catalyst comprising mixing alumina with water and ahydrolyzeable titanium compound under non-acidic conditions. Group VIIIand Group VIB metals are subsequently impregnated into the inorganicsupport.

The method described in U.S. Pat. No. 4,196,101 differs from the methodof our invention in that our invention involves mixing the Group VIIIand Group VIB metals rather than impregnating these metals into theorganic support.

U.S. Pat. No. 4,465,790 discloses a hydrodenitrogenation catalystcomprising molybdenum and nickel on a catalyst support consisting ofco-precipitated alumina and titania.

The method described in U.S. Pat. No. 4,465,790 differs from the methodof our invention in that alumina and titania are not co-precipitated.Instead, the gelled Group IVB metal compound is mixed with a supportingoxide, the Group VIB and Group VIII metal components.

U.S. Pat. No. 4,444,655 discloses the use of a hydrotreating catalyst ina process for hydrotrealing a heavy hydrocarbon oil containingasphaltenes. The hydrotreating catalyst utilizes inorganic oxidesselected from Groups II, III and IV of the Periodic Table. The catalyticmetal components are selected from metals belonging to Groups VB, VIB,VIII and IB of the Periodic Table.

The catalyst of the '655 patent has an average diameter of about 180angstroms to about 500 angstroms, with total volume of such pores beinglarger than about 0.2 cc/g.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a mixedcomposition comprising: (a) a supporting oxide; (b) a gelled Group IVBpromoter; (c) hydrogenation components including at least one componentfrom a Group VIII metal and at least one component from a Group VIBmetal.

There is also provided a method for making a hydrotreating catalystwhich comprises: (a) precipitating a hydrolyzeable Group IVB compound toform a hydrated Group IVB oxide gel; (b) washing the hydrated Group IVBoxide gel with water to substantially remove non-Group IVB components;(c) adding aqueous acidic compounds and a soluble Group VIII metalcompound to the hydrated Group IVB oxide gel, forming a slurry; (d)mixing and peptizing a hydrated supporting oxide with the slurry; (e)adding a partially or totally soluble Group VIB metal compound; (f)shaping, drying and calcining catalyst particles, and the use of acatalyst so prepared in a process for removing nitrogen from anitrogen-containing hydrocarbon feed. The denitrogenation processcomprises contacting the hydrocarbon stream under hydrodenitrogenationconditions and in the presence of hydrogen with the aforesaid catalyst.

Hydrodenitrogenating in accordance with the present invention resultsnot only in substantial nitrogen removal, but also results insubstantial RCR reduction of the feedstock, and sulfur removal.

Thus, among other factors, the present invention is based on ourdiscovery that the use of a gelled Group IVB metal compound, preferablya titanium compound when mixed with a supporting oxide, the Group VIBand Group VIII metal components, acts as a promoter for increasinghydrodenitrogenation activity of the catalytic metal, i.e., the GroupVIB and Group VIII metal components, present in the catalyst.

DETAILED DESCRIPTION OF THE INVENTION

As indicated previously, the composition of the present inventioncomprises: (a) a supporting oxide; (b) a gelled Group IVB promoter; (c)hydrogenation components including at least one component from a GroupVIII metal and at least one component from a Group VIB metal.

The Group IVB metals which can be used as promoters include titanium,zirconium and hafnium.

The supporting oxide used is alumina.

The hydrogenation components may be selected from among the metalsbelonging to Groups VIB and VIII of the Periodic Table, preferablynickel, cobalt, molybdenum and tungsten. Table I summarizes the range ofmetals which can be used in making the catalyst.

Most preferably, the catalyst comprises an aluminum oxide support, atitanium promoter, and nickel and molybdenum hydrogenation components.

                  TABLE I                                                         ______________________________________                                        Metal                                                                         Component    Broad, wt. %                                                                             Preferred, wt. %                                      ______________________________________                                        Ti           0.5-10.0   2.5-6.5                                               Zr           1.0-20.0   4.5-12.5                                              Hf           2.0-40.0   9.0-24.0                                              Ni           1.0-15.0   5.0-10.0                                              Co           1.0-15.0   5.0-10.0                                              Mo           5.0-25.0   10.0-20.0                                             W            10.0-50.0  20.0-40.0                                             ______________________________________                                    

The catalyst may be further impregnated using standard impregnatingprocedures and compounds such as phosphoric acids, ammonium phosphatesalts, and heteropolyphosphomolybdic acid.

The catalyst of this invention has a pore volume falling within a rangeof 0.30-0.60 cc/g and pore size distribution peaks falling within arange of 50-100 angstroms. The pore size distributions are relativelynarrow with at least 50% of the total pore volume contained in poreswith diameters falling within 20 angstroms of the peak.

Preferably, the catalyst of this invention has a pore volume fallingwithin a range of 0.37-0.52 cc/g and pore size distribution peaksfalling within a range of 60-90 angstroms. The pore size distributionsare relatively narrow with at least 60% of the total pore volumecontained in pores with diameters falling within 20 angstroms of thepeak.

A method is also presented as part of the invention for making thecomposition wherein a hydrolyzeable Group IVB compound is precipitatedto form a Group IVB oxide gel. The hydrated Group IVB oxide gel issubsequently washed. The preferred Group IVB compounds used to make thecatalyst are titanium compounds. These include the hydrolyzeabletitanium compounds. There are many sources of hydrolyzeable titaniumcompounds. Alkyl titanates such as tetrabutyl titanate or chelatedtitanium species such as the acetyl acetonate complexes or lactic acidsalts may be used. Most preferably, inorganic titanium compounds such astitanium sulfate or various titanium halides may be used.

When aqueous acidic compounds and a soluble Group VIII metal compound isadded to the hydrated Group IVB oxide gel, a slurry is formed. Thehydrated supporting oxide is mixed and peptized with the slurry. Aqueousacid compounds which can be used in our method include acetic acid,nitric acid, sulfuric acid, oxalic acid, hydrochloric acid and formicacid. However, other acid compounds can be used in our method. Thepreferred Group VIII metal compounds which may be used to make thecatalyst are nickel compounds. These include nickel acetate, nickelnitrate, nickel sulfate, nickel oxide, nickel chloride, nickel carbonateand nickel hydroxide and mixtures thereof.

A soluble Group VIB metal compound is added to the peptized mixture. Thepreferred Group VIB metal compounds used in making our catalyst ismolybdenum. These include ammonium molybdate, ammonium compounds ofmolybdenum oxides, molybdenum oxides and their hydrogen peroxidesolutions.

It is preferable to use metal compounds which are readily soluble inappropriate solutions. Readily soluble metal compounds are notnecessarily totally dissolved in the appropriate solution.

The composition is then extruded, dried to remove volatiles, and thencalcined in air at a temperature of from about 750° F. to about 1250° F.for about 1/2 to 4 hours.

The catalyst of the present invention can be used for hydroprocessing,e.g., hydrotreating, hydrocracking or the like. According to onepreferred embodiment of the present invention, the present catalyst isused in a hydrotreating process to reduce the nitrogen and sulfurcontent and RCR. Suitable hydrotreating feedstocks include anyhydrocarbon feedstock containing nitrogen with a boiling point greaterthan 500° F. This includes unprocessed and partially hydrodemetallizedvacuum and atmospheric residua and crude deasphalted oil, vacuum gasoil, heavy crude oils and lube oil.

These feedstocks can be passed over the catalyst of the presentinvention at a liquid hourly space velocity in a reactor of about 0.05to about 5.0, preferably from about 0.1 to about 3.0, while maintainingthe reaction zone at a temperature of from 500° F. to about 850° F.,preferably from about 550° F. to about 800° F., while under a totalpressure of about 450 to about 3500 pounds per square inch gauge,preferably from about 600 to about 2800 pounds per square inch gauge,and a hydrogen partial pressure of from about 350 to about 3200 poundsper square inch gauge, preferably from about 500 to about 2500 poundsper square inch gauge.

EXAMPLE 1

TiCl₄ was titrated with ammonium hydroxide to a pH of 7 to form ahydrated titania gel. The excess chloride ions were washed out withammonium acetate solution.

EXAMPLE 2

A catalyst is prepared using ammonium heptamolybdate (AHM).

685 gms of a TiO₂ gel, as prepared in Example 1, were well mixed with191 gms deionized water. While mixing, 193 gms glacial acetic acid wereadded to the slurry. Then 214 gms basic nickel carbonate were added. Theslurry was mixed until CO₂ evolution essentially ceased. Then, 108.6 gmsnitric acid (70% HNO₃) were slowly added to the slurry. This slurry waslabeled "2A".

30 gms hydrogen peroxide solution (30% H₂ O₂) were mixed with 151 ccdeionized water. 347 gms AHM were slowly added and stirred untildissolved. This solution was labeled Solution "2B".

1023 gms of pseudo boehmite alumina powder (760 gms dry-basis Al₂ O₃)were charged to a sigma-blade mixer. Slurry 2A was added while mixing.After 20 minutes, Solution 2B was added while mixing. After 20 minutesmixing, the wet mix was extruded.

The extrudates were dried and calcined at 950° F. for 1 hour withflowing dry air to give the final calcined catalyst.

EXAMPLE 3

Another catalyst of this invention was prepared using MoO₃. 108.6 gmsnitric acid (70% HNO₃) were added to 200 gms of deionized water. Thissolution was labeled "3A".

287 gms of a TiO₂ gel, as prepared in Example 1, were well mixed with300 gms deionized water. While mixing, 400 gms of nickel acetatetetrahydrate [Ni(C₂ H₃ O₂)₂ ·4H₂ O] were added to the slurry. Thisslurry was labeled "3B".

A molybdenum solution was prepared by stirring and filtering a mixturecomposed of 26.5 wt. % concentrated aqueous NH₄ OH, 28.9 wt. % MoO₃,balance deionized water. 100 cc concentrated aqueous NH₄ OH were mixedwith 753 cc of the molybdenum solution. The resultant solution waslabeled "3C".

1000 gms of pseudo boehmite alumina powder (760 gms dry-basis Al₂ O₃)were charged to a sigma-blade mixer. Solution 3A was added while mixing.Then Slurry 3B was added while mixing. Finally, Solution 3C was added.After another 20 minutes mixing, the wet mix was extruded.

The extrudates were dried and calcined at 1000° F. for 1 hour withflowing dry air to give the final calcined catalyst.

Examples 4 through 6 illustrate different methods which can be used toprepare various hydrotreating catalysts. These catalysts contain atitania-alumina inorganic oxide support and nickel and molybdenumhydrogenation components.

EXAMPLE 4

A comparative catalyst was prepared using Ti(OH)4.

286.5 gms Ti(OH)₄, an aqueous commercially available titanium source[titanium hydrolysate], were mixed with stirring in 300 gms of deionizedwater. 400 gms Ni(C₂ H₃ O₂)₂ ·4H₂ O [nickel acetate tetrahydrate] werethen slowly added with continued stirring. This mixture was labeled"4A".

108.6 gms nitric acid (70% HNO₃) were added to 200 gms of deionizedwater. This solution was labeled "4B".

A molybdenum solution was prepared by stirring and filtering a mixturecomposed of 26.5 wt. % concentrated aqueous NH₄ OH, 28.9 wt. % MoO₃,balance deionized water. 100 cc concentrated aqueous NH₄ OH were mixedwith 753 cc of the molybdenum solution. The resultant solution waslabeled "4C".

1000 gms of pseudo boehmite alumina powder (760 gms dry-basis Al₂ O₃)was charged to a sigma-blade mixer. Solution 4B was added and mixingcontinued for 10 minutes. Solution 4A was added and mixing continued for10 minutes.

Solution 4C was then added and the mixing was continued for anadditional 20 minutes. The wet mix was extruded.

The extrudates were dried and calcined at 1150° F. for 2 hours withflowing dry air to give the final catalyst.

EXAMPLE 5

A comparative catalyst was prepared using finely divided TiO₂.

108.6 gms of nitric acid (70% HNO₃) were diluted with 200 gms ofdeionized water. 400 gms of Ni(C₂ H₃ O₂)₂ ·4H₂ O [nickel acetatetetrahydrate] were then dissolved. This solution was labeled "5A".

85.2 gms of (TiO₂) [anatase titania] were stirred in 199 gms ofdeionized water. This slurry was labeled "5B".

A molybdenum solution was prepared by stirring and filtering a mixturecomposed of 26.5 wt. % concentrated aqueous NH₄ OH, 28.9 wt. % MoO₃,balance deionized water. 100 cc concentrated aqueous NH₄ OH were mixedwith 753 cc of the molybdenum solution. The resultant solution waslabeled "5C".

1000 gms of pseudo boehmite alumina powder (760 gms dry-basis Al₂ O₃)was charged to a sigma-blade mixer. Solution 5A was added while mixing.Then Slurry 5B was added while mixing. After an additional 10 minutes ofmixing, Solution 5C was added and the mixing was continued for anadditional 20 minutes. The wet mix was extruded.

The extrudates were dried and calcined at 950° F. for 1 hour usingflowing dry air.

EXAMPLE 6

A comparative catalyst was prepared from co-precipitated titania-aluminapowder.

35 gms of nitric acid (70% HNO₃) were diluted with 35 cc of deionizedwater. The solution was labeled "6A".

304 gms of nickel nitrate [Ni(NO₃)₂ ·6H₂ O[] were dissolved in 375 ccdeionized water. Then Solution 6A was added. This solution was labeled"6B".

A molybdenum solution was prepared by stirring and filtering a mixturecomposed of 26.5 wt. % concentrated aqueous NH₄ OH, 28.9 wt. % MoO₃,balance deionized water. 16.8 cc concentrated aqueous NH₄ OH was mixedwith 515 cc of the molybdenum solution. 35 cc deionized water wereadded. This solution was labeled "6C".

700 gms of a commercially available 10%/90% TiO₂ /Al₂ O₃ powder werecharged to a sigma-blade mixer. Solution 6B was added with mixing.Mixing was continued for an additional 20 minutes.

Solution 6C was then added and mixing was continued for an additional 20minutes. The wet mix was extruded.

The extrudates were dried and calcined at 950° F. for 1 hour withflowing dry air to give the final calcined catalyst.

EXAMPLE 7

In this example, the catalyst of Example 3 is contrasted with thecomparative catalysts of Examples 4-6 and commercial residuum catalysts.The feed used in this comparison was an Alaska North Slope straight runvacuum residuum having the properties shown in Table lI.

                  TABLE II                                                        ______________________________________                                        Gravity, °API                                                                             7.0                                                        Sulfur, wt. %      2.29                                                       Nitrogen, wt. %    0.78                                                       Oxygen, wt. %      0.51                                                       Ramsbottom Carbon, wt. %                                                                         17.9                                                       Micro-carbon Residue                                                                             17.9                                                       Asphaltenes, wt. % 3.21                                                       Ni/V/Fe, ppm       36/76/3                                                    Distillation, vol. %                                                          St/5                922/1012° F.                                       10/20              1017/1047° F.                                       ______________________________________                                    

An alternative way of measuring Ramsbottom Carbon is using ASTMD4530-85. The number obtained is referred to as Micro-carbon Residue.

The hydrotreating conditions used for this example are listed in TableIII:

                  TABLE III                                                       ______________________________________                                        Total pressure, psig    2000                                                  Feed rate (LHSV), hr..sup.-1                                                                          0.5                                                   Hydrogen/hydrocarbon feed rate, scf/bbl                                                               5000                                                  ______________________________________                                    

The catalysts were activated by a pre-sulfiding step before contact withthe hydrocarbon feed.

The catalysts of Examples 3-6 were compared for residuum conversion byrunning to constant sulfur removal (HDS), while monitoring nitrogenremoval (HDN) and micro-carbon residue (MCR) removal. The measure ofcatalyst performance was the normalized catalyst temperature required tomeet target product properties. Table IV compares the performance of thecatalyst of this invention (Example 3) with the comparative catalysts ofExamples 4-6, and with comparative commercial nickel, molybdenum,phosphorous, alumina residuum processing catalysts (catalysts A, B).

In this test, a good catalyst deactivates rapidly for 300-400 hoursbefore lining out at a lower deactivation rate. To compare thesecatalysts, we compared normalized activities at 600 hours. However, if acatalyst is fouling very rapidly with obviously poor activity, wesometimes stop the test before 600 hours. Table IV contains data at 600hours for those tests which ran that long and for shorter periods fortests which were stopped early.

                  TABLE IV                                                        ______________________________________                                                                         Catalyst                                                                             Catalyst                              Ex 3          Ex 4   Ex 5   Ex 6 A      B                                     ______________________________________                                        Run Hrs.                                                                              300    600    600  300  400  400    250                               Normalized                                                                    Catalyst                                                                      Temp. °F.                                                              HDS     732    743    766  749  770  755    768                               MCR     732    740    751  736  776  768    765                               HDN     731    741    756  749  779  765    --                                ______________________________________                                    

What is claimed is:
 1. A method of hydrodenitrogenation of a hydrocarbonfeed containing nitrogen compounds, which method comprises contactingsaid feed in a reaction zone under hydrodenitrogenation conditionscomprising a temperature within the range of about 500° F. to about 850°F., a total pressure within the range of about 450 to about 3500 poundsper square inch gauge, its space velocity ranging from 0.05 to about 5.0(hr.-¹), and a hydrogen partial pressure ranging from about 350 to about3200 pounds per square inch gauge in the presence of hydrogen and with acatalyst prepared by the method comprising:a. precipitating ahydrolyzable Group IVB compound to form a hydrated Group IVB oxide gel;b. washing the hydrated Group IVB oxide gel with water; c. addingaqueous acidic compounds and a soluble Group VIII metal compound to thehydrated Group IVB oxide gel, forming a slurry; d. mixing and peptizinga hydrated supporting oxide with the slurry; e. adding a partially ortotally soluble Group VIB metal compound; and f. shaping, drying andcalcining catalyst particles; and collecting an effluent with reducednitrogen levels.
 2. The method of claim 1 wherein said aqueous acidiccompounds are selected from the group consisting of nitric acid,sulfuric acid, formic acid, acetic acid, oxalic acid and hydrochloricacid.
 3. The method of claim 1 wherein said Group VIII metal compoundcontains nickel.
 4. The method of claim 1 wherein said Group VIB metalcompound contains molybdenum.
 5. A method of hydrodenitrogenation of ahydrocarbon feed containing nitrogen compounds, which method comprisescontacting said feed in a reaction zone under hydrodenitrogenationconditions comprising a temperature within the range of about 500° F. toabout 850° F., a total pressure within the range of about 450 to about3500 pounds per square inch gauge, its space velocity ranging from about0.05 to about 5.0 (hr.-¹), and a hydrogen partial pressure ranging fromabout 350 to about 3200 pounds per square inch gauge, in the presence ofhydrogen and with a catalyst prepared by the method comprising:a.precipitating a hydrolyzable titanium compound to form a hydratedtitanium oxide gel; b. washing the hydrated titanium oxide gel withwater to substantially remove non-titanium compounds; c. adding aqueousacidic compounds and a soluble nickel compound to the hydrated titaniumoxide gel, forming a slurry; d. mixing and peptizing a hydrated aluminawith the slurry; e. adding a soluble molybdenum compound; f. shaping,drying and calcining catalyst particles; and collecting an effluent withreduced nitrogen levels.
 6. The method of claim 5 wherein the titaniumcompound is titanium tetrachloride.
 7. The method of claim 5 whereinsaid nickel compound is selected from the group consisting of nickelacetate, nickel nitrate, nickel sulfate, nickel oxide, nickel chloride,nickel carbonate, nickel hydroxide and mixtures thereof.
 8. The methodof claim 5 wherein said molybdenum compound is selected from the groupconsisting of ammonium molybdate, ammonium compounds of molybdenumoxides, molybdenum oxides and their hydrogen peroxide solutions.
 9. Themethod of claim 1 or 5 wherein the catalyst particles, after calcining,are impregnated with a phosphorous-containing compound.
 10. The methodof claim 9 wherein said phosphorous-containing compound is selected fromthe group consisting of phosphoric acid, ammonium phosphate, andphosphomolybdic acid.
 11. The method of claim 5 wherein said conditionscomprise a temperature within the range of about 550° F. to about 800°F., a total pressure within the range of about 600 to about 2800 poundsper square inch gauge, a space velocity ranging from about 0.1 to about3.0(hr.⁻¹), and a hydrogen partial pressure ranging from about 500 toabout 2500 pounds per square inch gauge.
 12. The method of claim 11 or 5which further reduces the Ramsbottom Carbon Residue of the hydrocarbonfeed.
 13. The method of claim 1 or 5 which further reduces the sulfurcontent of the hydrocarbon feed.